Use colour strategically. Colour in forms should be used with care - but used well it can really aid form completion and navigation. In general, yellow, for example, is a colour to avoid as much as possible - text set in yellow on a typical light background can be very hard to read - and people can find yellow aggressive.

It is similarly annoying to them when it is a long free text box, making the customer question whether they are answering correctly and sufficiently. Providing response boxes that reflect the anticipated answer length and format reassures people that they are filling them in correctly.